!Magister Justin:

You can get the next stone by killing* the Archon of Halisha* in the Four Sepulchers. You'll need help to gain entry.%%
If that proves too difficult, go to the* Shrine of the Loyal* and slay Halisha's minions. If you collect 700* Halisha's Marks*, the Archon will appear.%%
The minions include* Grave Scarabs, Scavenger Scarabs, Grave Ants, Scavenger Ants, Shrine Knights, and Shrine Guards*.